Howard has considerable expertise in the field and has collaborated on many projects with like-minded enthusiasts. He has digitised a wealth of information and made it available to fellow enthusiasts and researchers.
I hesitate to mention Pete Young as if you visit his site you may think you've followed Alice down the rabbit hole. Honorable mention. (1)
Sergio, who hails from Argentina, has contributed numerous articles on rare and interesting machines. He tends to react with some embarrassment if referred to as an historian, so let's just say he's an ardent and thorough multilingual researcher.
Murray Barnard has developed one of the most venerable motorcycle sites on the internet, which includes a detailed listing of veteran Russian and almost all known Australian marques.
Contributed many articles on NSU and other marques written mostly in the 1990s.
Prolific photographer and author of several books on Austrian motorcycles
Whilst not actually a motorcycle researcher, Andrew (Melbourne, Australia) has supplied many rare and interesting images, in particular from Eastern Bloc countries. His specialty is photographic art and he has compiled galleries consisting of tens of thousands of high quality images.
Denis Quinlan, aka Velobanjogent, a very knowledgeable contributor from Australia.
Eric Tindal, marque specialist from the VMCC supplied information on the Moto Reve and other machines.
Author of papers and articles on Greek history.
Journalist and Hungarian marque specialist.
Phil Aynsley has photographically documented a vast number of motorcycles in museums and collections around the world. A walking encyclopedia of the Italian diaspora, his image descriptions are collated from owners and curators.
Many more historians and marque specialists not specifically mentioned here are referenced in the bibliography and also on the pages devoted to museums and collections.
1. Intended as humour, but sometimes it fails to translate. No disrespect intended, quite the opposite.